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Aggregation128Utils#

public class Aggregation128Utils#

Utility methods for breaking apart and reassembling 128-bit values during aggregations to enable hash-based aggregations and detect overflows.

Method Summary

combineInt64SumChunks(Table chunks, DType type)

Reassemble a column of 128-bit values from a table of four 64-bit integer columns and check for overflow.

extractInt32Chunk(ColumnView col, DType outType, int chunkIdx)

Extract a 32-bit chunk from a 128-bit value.

Static Methods

public static ColumnVector extractInt32Chunk(
ColumnView col,
DType outType,
int chunkIdx
)#

Extract a 32-bit chunk from a 128-bit value.

Parameters:

  • col – column of 128-bit values (e.g.: DECIMAL128)

  • outType – integer type to use for the output column (e.g.: UINT32 or INT32)

  • chunkIdx – index of the 32-bit chunk to extract where 0 is the least significant chunk and 3 is the most significant chunk

Returns:

column containing the specified 32-bit chunk of the input column values. A null input row will result in a corresponding null output row.

public static Table combineInt64SumChunks(Table chunks, DType type)#

Reassemble a column of 128-bit values from a table of four 64-bit integer columns and check for overflow.

The 128-bit value is reconstructed by overlapping the 64-bit values by 32-bits. The least significant 32-bits of the least significant 64-bit value are used directly as the least significant 32-bits of the final 128-bit value, and the remaining 32-bits are added to the next most significant 64-bit value. The lower 32-bits of that sum become the next most significant 32-bits in the final 128-bit value, and the remaining 32-bits are added to the next most significant 64-bit input value, and so on.

Parameters:

  • chunks – table of four 64-bit integer columns with the columns ordered from least significant to most significant. The last column must be of type INT64.

  • type – the type to use for the resulting 128-bit value column

Returns:

table containing a boolean column and a 128-bit value column of the requested type. The boolean value will be true if an overflow was detected for that row’s value when it was reassembled. A null input row will result in a corresponding null output row.